S2006-IPI
6. DTN Routing (2): Probabilistic / Un-Planned / Unknown Connectivity Pattern
Topics
10. Data Retrieval in Intermittedly Connected Networks
So you´ve got the net, now what about the data it should deliver? After examining different aspects of DTNs from TCP replacements over routing to network coding, this section deals with the actual transport of data. We have a look at two interesting papers: the first one presents a rather new approach to delivery of data, the other one identifies some flaws in the current (2006) DTN architecture that affect data delivery and proposes some enhancements to correct these.
To have a first shallow insight, have a look at our Introductory Speech Slides (PDF)
Distributed Information Retrieval
Enhanced Disruption and Fault Tolerant Network
First, I'll try to clarify some DTN-related things and buzzwords, to be able to explain which flaws of the current design EDIFY tries to correct. I'll concentrate on aspects that relate to EDIFY.
The concept of the DTN research group views as DTN as a network of networks, as some sort of overlay on top of other nets, being able to support communication between these (maybe diverse) nets. These possibly diverse nets are also called region in DTN terminology ([1]).
DTN-wide addressing is now done via a tuple (region,locator), where region marks a network and locator a node belonging to this network. Note that addressing within a region/network can be completely different, it's up to the network how this is done. The (R,L)-addresses are specific to the overlying DTN, used to do inter-group addressing.
To actually be able to communicate with different regions, each region possesses at least one special gateway node, translating between the region's own protocol and DTN-speak and resolving global (R,L)-style DTN names into local, region-specific ones.
While this addressing scheme is quite fine with static regions, it is unable to deal with ad hoc and mobile regions: The assumption that is made is that nodes within a region are always able to communicate with their region members. But in reality, this isn't true: regions/networks can be split, i.e. the communication within the region can be disrupted (imagine a platoon of soldiers having to split due to enemy fire)
I tried to summarize the paper in these slides.